Polycarbonate-ABS moulding materials

ABSTRACT

A thermoplastic molding composition containing 1 to 99 parts by weight of aromatic polycarbonate or polyester carbonate and 1 to 99 parts by weight of at least one graft polymer prepared by solution polymerization is disclosed. The graft polymer is characterized in having rubber content of 20 to 50 wt. % and in that the average particle size of its rubber phase is 80 to 600 nm. The composition, which optionally contains additives, flameproofing agents and reinforcing agents, is characterized by its improved mechanical properties.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

The present patent application claims the right of priority under 35U.S.C. §119 (a)-(d) and 35 U.S.C. §365 of International Application No.PCT/EP98/05884, filed Sep. 16, 1998, which was published in German asInternational Patent Publication No. WO 99/16828 on Apr. 8, 1999, whichis entitled to the right of priority of German Patent Application Number197 42 868.1, filed Sep. 29, 1997.

The present invention relates to polycarbonate-ABS moulding compositionshaving excellent mechanical properties, in particular an excellentstress cracking behaviour, a high notched impact strength and a highjoint line strength.

Polycarbonate-ABS moulding compositions are sufficiently well known (forexample, EP-A 363 608, EP-A 345 522, EP-A 640 655).

A specific field of application of these moulding compositions is theproduction of mouldings having a very. good impact strength. Specialgraft rubbers prepared by emulsion polymerisation are preferably used inorder to obtain or to attain rubber-specific properties in thesemoulding compositions. The level of the values for the known mouldingcompositions and of the mouldings produced from them is not alwaysadequate for the production of mouldings having increased impact stressand elastic strain. An increase in the proportion of these graft rubbersprepared by emulsion polymerisation then frequently results in mouldingcompositions having significant disadvantages as regards theirproperties (heat deflection temperature, modulus of elasticity).

The object of the present invention is therefore to providepolycarbonate-ABS moulding compositions having excellent mechanicalproperties, such as an outstanding notched impact strength, an excellentjoint line strength, a high modulus of elasticity and a very high stresscracking resistance.

It has now surprisingly been found that the use of particularABS-polymers leads to polycarbonate-ABS moulding compositions which canbe processed to form mouldings having a very good standard of mechanicalproperties, in particular having an excellent notched impact strength, ahigh joint line strength, a high modulus of elasticity and anoutstanding long-term strength.

The present invention accordingly provides thermoplastic mouldingcompositions containing

A 1 to 99, preferably 15 to 80, particularly preferably 30 to 70 partsby weight of an aromatic polycarbonate or polyester carbonate and

B 1 to 99, preferably 15 to 80, particularly preferably 30 to 70 partsby weight of at least one graft polymer prepared by solutionpolymerisation and having a rubber content of from 20 to 50 wt. %,preferably from 22.5 to 45 wt. % and particularly preferably from 25 to40 wt. %, based on the graft polymer, and an average particle diameterof the rubber phase of from 80 to 600 nm, preferably from 150 to 400 nmand particularly preferably from 200 to 350 nm,

the sum of all the components of the moulding compositions according tothe invention amounting to 100 parts by weight.

Component A

Aromatic polycarbonates and/or aromatic polyester carbonates which aresuitable according to the invention as component A are known in theliterature or can be prepared by methods known in the literature (forthe preparation of aromatic polycarbonates, see, for example, Schnell,“Chemistry and Physics of Polycarbonates”, Interscience Publishers,1964, as well as DE-AS 1 495 626, DE-OS 2 232 877, DE-OS 2 703 376,DE-OS 2 714 544, DE-OS 3 000 610, DE-OS 3 832 396; for the preparationof aromatic polyester carbonates, for example, DE-OS 3 007 934).

Aromatic polycarbonates are prepared, for example, by reaction ofdiphenols with carboxylic halides, preferably phosgene and/or witharomatic dicarboxylic dihalides, preferably benzenedicarboxylicdihalides, by the phase interface method, optionally using chainstoppers, for example, monophenols and optionally using trifunctional ormore than trifunctional branching agents, for example, triphenols ortetraphenols.

Suitable aromatic polycarbonates according to the invention are inparticular those based on the diphenols corresponding to formula (I)

wherein

A denotes a single bond, C₁-C₅-alkylene, C₁-C₅-alkylidene,C₅-C₆-cycloalkylidene, —S—, —SO₂—, —O—, —CO— or C₆-C₁₂-arylene, whichmay optionally be condensed with other aromatic rings containing heteroatoms,

B independently of one another, denotes halogen, C₁-C₈-alkyl,C₆-C₁₀-aryl, preferably chlorine, bromine, phenyl, C₇-C₁₂-aralkyl, forexample, benzyl,

x independently of one another, denotes respectively 0, 1 or 2 and

p denotes 1 or 0,

or alkyl-substituted dihydroxyphenylcycloalkanes corresponding toformula (II),

wherein

R¹ and R², independently of one another, denote hydrogen, halogen,preferably chlorine or bromine, C₁-C₈-alkyl, preferably C₁-C₄-alkyl, forexample, methyl, ethyl, C₅-C₆-cycloalkyl, C₆-C₁₀-aryl, preferablyphenyl, or C₇-C₁₂-aralkyl, preferably phenyl-C₁-C₄-alkyl, in particularbenzyl,

m is an integer from 4 to 7, preferably 4 or 5,

R³ and R⁴, individually selectable for each Z and independently of oneanother, denote hydrogen or C₁-C₆-alkyl, preferably hydrogen, methyl orethyl and

Z denotes carbon, with the proviso that on at least one atom Z, R³ andR⁴ simultaneously denote alkyl, preferably methyl.

Preferred diphenols are hydroquinone, resorcinol, dihydroxydiphenyl,bis(hydroxyphenyl)-C₁-C₅-alkanes, bis(hydroxyphenyl)-C₅-C₆-cycloalkanes,bis(hydroxyphenyl) ethers, bis(hydroxyphenyl) sulphoxides,bis(hydroxyphenyl) ketones, bis(hydroxyphenyl) sulphones andα,α-bis(hydroxyphenyl)diisopropylbenzenes as well as theirring-brominated and/or ring-chlorinated derivatives.

Particularly preferred diphenols are diphenylphenol, bisphenol A,2,4-bis(4-hydroxyphenyl)-2-methylbutane,1,1-bis(4-hydroxyphenyl)cyclohexane,1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane,4,4′-dihydroxydiphenyl sulphide, 4,4′-dihydroxydiphenyl sulphone as wellas their di- and tetrabrominated or chlorinated derivatives such as, forexample, 2,2-bis(3-chloro-4-hydroxyphenyl)propane,2,2-bis(3,5-dichloro-4-hydroxyphenyl)propane or2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane.

2,2-bis(4-hydroxyphenyl)propane (bisphenol A) is preferred inparticular.

The diphenols may be used separately or be mixed together in anyproportions.

The diphenols are known in the literature or are obtainable by methodsknown in the literature.

Suitable chain stoppers for the preparation of the thermoplastic,aromatic polycarbonates are, for example, phenol, p-chlorophenol,p-tert. butylphenol or 2,4,6-tribromophenol, also long-chainalkylphenols, such as 4-(1,3-tetramethylbutyl)phenol according to DE-OS2 842 005 or monoalkylphenol or dialkylphenols having a total of 8 to 20C atoms in the alkyl substituents, such as 3,5-di-tert. butylphenol,p-isooctylphenol, p-tert. octylphenol, p-dodecylphenol and2-(3,5-dimethlheptyl)phenol and 4-(3,5-dimethylheptyl)phenol. Thequantity of chain stoppers to be used is generally between 0.5 mol-% and10 mol-%, based on the molar sum of the diphenols used in each case.

The thermoplastic, aromatic polycarbonates have average weight averagemolecular weights (M_(w), determined, for example, by ultracentrifuge orlight-scattering measurement) of from 10,000 to 200,000, preferably20,000 to 80,000.

The thermoplastic, aromatic polycarbonates may be branched in knownmanner, and in fact preferably by the incorporation of from 0.05 to 2.0mol-%, based on the sum of the diphenols used, of ≧trifunctionalcompounds, for example, those having ≧three phenolic groups.

Both homopolycarbonates and copolycarbonates are suitable. To preparecopolycarbonates as component A) according to the invention, it is alsopossible to use from 1 to 25 wt. %, preferably 2.5 to 25 wt. % based onthe total quantity of diphenols used, of polydiorganosiloxanes havinghydroxy-aryloxy end groups. These are known (see, for example, U.S. Pat.No. 3,419,634) or can be prepared by methods known in the literature.The preparation of copolycarbonates containing polydiorganosiloxanes isdescribed, for example, in DE-OS 3 334 782.

Besides the bisphenol A homopolycarbonates, preferred polycarbonatesinclude the copolycarbonates of bisphenol A with up to 15 mol-%, basedon the molar sum of diphenols, of diphenols other than those mentionedas being preferred or particularly preferred, and in particular of2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane.

Aromatic dicarboxylic dihalides for the preparation of aromaticpolyester carbonates are preferably the diacid dichlorides ofisophthalic acid, terephthalic acid, diphenylether-4,4′-dicarboxylicacid and of naphthalene-2,6-dicarboxylic acid.

Mixtures of the diacid dichlorides of isophthalic acid and ofterephthalic acid in the ratio of 1:20 and 20:1 are particularlypreferred.

For the preparation of polyester carbonates, in addition a carboxylicacid halide, preferably phosgene, is used concomitantly as abifunctional acid derivative.

Possible chain stoppers for the preparation of the aromatic polyestercarbonates, apart from the monophenols already mentioned, are theirchloroformic esters as well as the acid chlorides of aromaticmonocarboxylic acids, which optionally may be substituted byC₁-C₂₂-alkyl groups or by halogen atoms, as well as aliphaticC₂-C₂₂-monocarboxylic chlorides.

The quantity of chain stoppers is from 0.1 to 10 mol-% in each case,based on mols of diphenols in the case of phenolic chain stoppers and onmols of dicarboxylic dichlorides in the case of monocarboxylic chloridechain stoppers.

The aromatic polyester carbonates may also contain incorporated aromatichydroxycarboxylic acids.

The aromatic polyester carbonates may be linear, or branched in knownmanner (regarding this, see also DE-OS 2 940 024 and DE-OS 3 007 934).

Compounds which can be used as branching agents are, for example,trifunctional or polyfunctional carboxylic chlorides, such as trimesictrichloride, cyanuric trichloride, 3,3′-4,4′-benzophenonetetracarboxylictetrachloride, 1,4,5,8-naphthalenetetracarboxylic tetrachloride orpyromellitic tetrachloride, in quantities of from 0.01 to 1 mol-% (basedon dicarboxylic dichlorides used), or trifunctional or polyfunctionalphenols, such as phloroglucinol,4,6-dimethyl-2,4,6-tri(4-hydroxyphenyl)hepten-2,4,4-dimethyl-2,4,6-tri(4-hydroxyphenyl)heptane,1,3,5-tri(4-hydroxyphenyl)benzene, 1,1,1-tri(4-hydroxyphenyl)ethane,tri(4-hydroxyphenyl)phenylmethane,2,2-bis[4,4-bis(4-hydroxyphenyl)cyclohexyl]propane,2,4-bis(4-hydroxyphenylisopropyl)phenol, tetra(4-hydroxyphenyl)methane,2,6-bis(2-hydroxy-5-methylbenzyl)-4-methylphenol),2-(4-hydroxyphenyl)-2-(2,4-dihydroxy-phenyl)propane,tetra(4-[4-hydroxyphenylisopropyl]phenoxy)methane,1,4-bis[4,4′-di-hydroxytriphenyl)methyl]benzene, in quantities of from0.01 to 1.0 mol-%, based on diphenols used. Phenolic branching agentsmay be introduced together with the diphenols and acid chloridebranching agents may be introduced together with the acid dichlorides.

The content of carbonate structural units in the thermoplastic, aromaticpolyester carbonates can be varied freely.

The content of carbonate groups is preferably up to 100 mol-%, inparticular up to 80 mol-% and particularly preferably up to 50 mol-%,based on the sum of ester groups and carbonate groups.

Both the ester content and the carbonate content of the aromaticpolyester carbonates may be in the form of blocks or be statisticallydistributed in the polycondensate.

The relative solution viscosity (η_(rel)) of the aromatic polyestercarbonates is within the range of 1.18 to 1.4, preferably 1.22 to 1.3(measured on solutions of 0.5 g polyester carbonate in 100 ml methylenechloride solution at 25° C.).

The thermoplastic, aromatic polycarbonates and polyester carbonates maybe used on their own or be mixed with one another in any proportions.

Component B

Graft polymers of the ABS type prepared by solution polymerisation areused as component B.

The graft polymer in component B is preferably radically polymerisedfrom a monomer mixture comprising

B.1 90 to 20 parts by weight aromatic monoalkenyl compounds,

B.2 0 to 50 parts by weight ethylenically unsaturated nitriles,

B.3 0 to 30 parts by weight of other copolymerisable compounds, in thepresence of

15 to 50 parts by weight, per 100 parts by weight of monomers B.1 toB.3, of a soluble, gel-free butadiene polymer or butadiene-styrenecopolymer and in the presence of

50 to 200 parts by weight of a solvent per 100 parts by weight ofmonomers B.1 to B.3,

wherein the solvent is an aliphatic (C₁-C₈) or cycloaliphatic (C₅-C₆)alcohol, ketone, ether, ester, nitrile (solvent S 1) or a mixture of(S 1) with an aliphatic, cycloaliphatic or aromatic hydrocarbon (solventS 2) in the weight ratio S 1:S 2 of from 100:0 to 30:70 and thepolymerisation is carried out until the polymer content of the totalmixture is 30 to 70 wt. %, with thorough mixing and optionallysubsequent addition of controller and initiator, so that the graftpolymer contains 20 to 50 wt. % butadiene polymer.

The total rubber content of the graft polymer is preferably from 22.5 to45 wt. %, particularly preferably from 25 to 40 wt. % and mostpreferably from 10 to 20 wt. %.

Component B is prepared by solution polymerisation with the use of atleast one solvent, selected from aliphatic (C₁-C₈) or cycloaliphatic(C₅-C₆) alcohols, ketones, ethers, esters, nitriles or a mixture of atleast one of the above-mentioned solvents with an aliphatic orcycloaliphatic C₄-C₁₀ hydrocarbon and/or aromatic hydrocarbon underspecial boundary conditions.

Here the polymer content of the total mixture is preferably 30 to 60 wt.%, in particular 35 to 50 wt. %, the total content of solvent is 25 to60 wt. % and the remainder of the mixture, to 100% in each case, isunreacted monomers.

In the preferred preparation of component B, where solvents or mixturesof solvents from the group (S 1) and optionally from the group (S 2) areused in the given weight ratios 1:0 to 3:7, despite high rubber contentsa phase inversion can successfully be passed through rapidly withsufficient conversions, so that a finely dispersed phase of graft rubberis formed.

The preparation of component B may be carried out in batches,semicontinuously and continuously.

In the continuous mode of operation, the solution of the monomers and ofthe rubber in the solvents may advantageously be polymerised in acontinuously filled and thoroughly mixed stirred-tank reactor with astationary conversion of monomers after the phase inversion of more than10 wt. %, based on the sum of the monomers, in the first step, and theradically initiated polymerisation can be continued in at least onefurther step until a conversion of monomers, based on the sum of themonomers, of from 30 to 70 wt. % is achieved, with thorough mixing inone or more additionally continuously operated stirred-tank reactors inseries or in a thoroughly mixing plug-flow reactor and/or a combinationof both reactor types, residual monomers and solvents can be removed byconventional techniques (for example, in a heat-exchanging evaporator,flash evaporator, extruder evaporator, film or layer evaporator,screw-type evaporator) and be returned to the process. It may also be ofadvantage to carry out the continuous polymerisation in three steps, thefirst step being operated with a stationary conversion of monomersbefore the phase inversion of less than 10 wt. % and the further stepsbeing operated at the conversions described above.

The batchwise or semicontinuous polymerisation can be carried out in oneor more filled or partly filled stirred-tank reactors arranged intandem, with previous addition or thorough mixing of the monomers, ofthe rubber and of the solvents and polymerisation until the specifiedconversion of monomers of 30 to 70 wt. % is attained.

For improved thorough mixing and distribution of the rubber introduced,in both the continuous and in the batchwise mode of operation thepolymer syrup can be pumped round in a cycle by means of mixing andshearing units. Such “loop operations” are prior art and may be usefulfor adjusting the particle size of the rubber. More advantageous,however, is the arrangement of shearing units between two separatereactors, in order to avoid back-mixing, which leads to a widening ofthe particle-size distribution.

The average residence time is 1 to 10 hours. The polymerisation isadvantageously carried out at 60° C. to 120° C., preferably at theboiling point of the solvent/polymer mixture. It is advantageous tocarry out the polymerisation at standard pressure. It is also feasible,however, to carry out the polymerisation at a slight excess pressure ofup to 6 bar.

The viscosities of the stirred or transported media are in the range ofat most 150 Pa·s.

The graft polymer can be isolated in known manner by precipitation insolvent, by stripping with water and/or steam or by evaporation untilthe polymer melts, for example, in flash evaporators, extruderevaporators, helical evaporators, film evaporators, certain layerevaporators, falling-film evaporators or screw-type evaporators.

Solvents and residual monomers can also be removed in stirred multiphaseevaporators equipped with kneaders and stripping devices. Theconcomitant use of blowing agents and entraining agents, for examplesteam, is possible here, but despite the high quantities of solvent avery low residual monomer content can be attained by simple evaporationmethods, even without the use of such entraining agents.

Solvents of the group (S 1) are alcohols such as methanol, ethanol,propanol, isopropanol, butanol, isobutanol, tert. butanol, amyl alcohol,isoamyl alcohol, isooctanol, cyclohexanol, ketones such as acetone,methyl ethyl ketone, methyl isopropyl ketone, cyclopentanone,cyclohexanone; ethers such as tetrahydrofuran, dioxane, ethylene glycoldimethyl, -diethyl, -dipropyl, -diisopropyl ether; esters such as ethylacetate, propyl acetate, butyl acetate or nitriles such as acetonitrile,propionitrile, butyronitrile. Preferably methyl ethyl ketone and acetoneare used.

Solvents of the group (S 2) are aliphatic hydrocarbons such as butane,pentane, hexane, heptane, octane and their respective iso-derivatives,cycloaliphatic hydrocarbons such as cyclopentane, cyclohexane,alkylcyclopentane, alkylcyclohexane, aromatic hydrocarbons such asbenzene, toluene, xylenes, ethylbenzene. Preferably toluene andethylbenzene are used.

Mixtures of acetone and ethylbenzene and mixtures of acetone and tolueneare particularly preferred.

It is also possible to use only solvents from the group (S 1). Methylethyl ketone is then preferred.

In order to adjust the molar masses, conventional substances forcontrolling molar mass, such as mercaptans and olefins, may be used, forexample, tert. dodecyl mercaptan, n-dodecyl mercapten, cyclohexane,terpinols, dimeric α-methylstyrene etc., in quantities of from 0.05 to1.0 wt. %, based on copolymerising monomers.

Suitable initiators for the radical polymerisation are peroxides activein grafting which dissociate into radicals; these peroxides includeperoxycarbonates, peroxydicarbonates, diacyl peroxides, perketals ordialkyl peroxides and/or azo compounds or mixtures thereof. Examples areazobisisobutyronitrile, azoisobutyric alkyl ester, tert. butylperpivalate, tert. butyl peroctoate, tert. butyl perbenzoate. Theseinitiators are used in quantities of from 0.01 to 1 wt. %, based onmonomers B.1 to B.3.

Conventional additives, for example, dyes, antioxidants, lubricants,stabilisers, which are known to the person skilled in the art, may beadded during the polymerisation or before the working up.

Suitable rubbers for the preparation of component B are preferablysoluble, gel-free butadiene polymers, for example, polybutadienes, alsostyrene-butadiene copolymers in statistical and/or block form, having ahigh 1,2-vinyl content of from 2 to 40%, preferably from 8 to 25%, basedon the double bonds, having molar masses of from 50,000 to 500,000, andincluding branched and radial polymers having gel contents of <1,000ppm.

Aromatic monoalkenyl compounds B.1 are preferably styrene,α-methylstyrene, ring-substituted alkylstyrenes, ring-substitutedchlorostyrenes.

Preferably acrylonitrile or methacrylonitrile are used as ethylenicallyunsaturated nitriles B.2.

Copolymerisable compounds B.3 are, for example, acrylic esters such asmethyl (meth)acrylate, ethyl (meth)acrylate, tert. butyl (meth)acrylate,esters of fumarate, itaconic acid, maleic derivatives such as maleicanhydride, maleic esters, N-substituted maleimides such asN-cyclohexylmaleimide or N-phenylmaleimide, N-alkylphenylmaleimide,acrylic acid, methacrylic acid, fumaric acid, itaconic acid or amidesthereof.

The ABS polymers B which are suitable according to the invention have arubber content of from 20 to 50 wt. %, preferably from 22.5 to 45 wt. %and particularly preferably from 25 to 40 wt. %, the average particlediameter is from 80 to 660 nm, preferably from 150 to 400 nm andparticularly preferably from 250 to 350 nm.

Furthermore the graft polymers B have a degree of grafting preferably of0.2 to 1 (cf. M. Hoffmann, H. Krömer, R. Kuhn in “Polymeranalytik I”,Georg Thieme Verlag Stuttgart 1977) and a gel content of from 30 to 50wt. % (measured in methyl ethyl ketone).

Besides component B according to the invention, conventional ABSpolymers may also be added (cf. EP-A 345 522 or 640 655).

In addition to components A and B according to the invention, themoulding compositions may contain further components, which aredescribed below, with examples. The quantitative data refer in each caseto the entire moulding composition.

Vinyl (co)polymers (component C.1) and/or polyalkylene terephthalates(component C.2), each in a quantity of up to 30 wt. % and preferably upto 20 wt. %, may be used as additional thermoplastics. The sum of allcomponents totals 100%.

Component C.1)

Vinyl (co)polymers usable according to the invention as component C.1)are resinous, thermoplastic and rubber-free. They are those composed ofat least one monomer from among styrene, α-methylstyrene, ring-alkylsubstituted styrene, C₁-C₈-alkyl acrylate, C₁-C₈-alkyl methacrylate(component C.1.1) together with at least one monomer from amongacrylonitrile, methacrylonitrile, C₁-C₈-alkyl methacrylate, C₁-C₈-alkylacrylate, maleic anhydride and/or N-substituted maleimide (componentC.1.2).

C₁-C₈-alkyl acrylates and C₁-C₈-alkyl methacrylates are esters ofacrylic acid and methacrylic acid respectively and of monohydricalcohols having 1 to 8 C atoms. Methyl methacrylate, ethyl methacrylateand propyl methacrylate are particularly preferred. A particularlypreferred methacrylate which may be mentioned is methyl methacrylate.

Thermoplastic copolymers having a composition corresponding to componentC.1) may be formed as secondary products during the graft polymerisationfor the preparation of component B), especially when large quantities ofmonomers are grafted onto small quantities of rubber. The quantity ofcopolymer C.1) to be used according to the invention does not includethese secondary products of the graft polymerisation.

The thermoplastic copolymers C.1) contain 50 to 95 wt. %, preferably 60to 90 wt. %, component C.1.1) and 5 to 50 wt. %, preferably 10 to 40 wt.%, component C.1.2).

Particularly preferred copolymers C.1) are those composed of styrene,with acrylonitrile and optionally with methyl methacrylate, ofα-methylstyrene with acrylonitrile and optionally with methylmethacrylate, or of styrene and α-methylstyrene with acrylonitrile andoptionally with methyl methacrylate.

The styrene-acrylonitrile copolymers used as component C.1) are knownand can be prepared by radical polymerisation, in particular by emulsionpolymerisation, suspension polymerisation, solution polymerisation orbulk polymerisation. The copolymers suitable as component C.1) havemolecular weights (weight average, determined by light scattering orsedimentation) of between 15,000 and 200,000.

Particularly preferred copolymers C.1) according to the invention arealso statistically constructed copolymers of styrene, maleic anhydrideand/or N-substituted maleimide which can be prepared from thecorresponding monomers by a continuous bulk polymerisation or solutionpolymerisation, with incomplete conversions.

The proportions of the two components of the statistically constructedstyrene-maleic anhydride copolymers suitable according to the inventionmay be varied within wide limits. The preferred content of maleicanhydride is between 5 and 25 wt. %.

The molecular weights (number average, n) of the statisticallyconstructed styrene-maleic anhydride copolymers suitable according tothe invention as component C.1) may vary within wide ranges. The rangefrom 60,000 to 200,000 is particularly preferred.

An intrinsic viscosity of 0.3 to 0.9 dl/g (measured in dimethylformamideat 25° C.) is preferred for these products.

Instead of styrene, the vinyl copolymers C.1) may containring-substituted styrenes such as vinyltoluenes, 2,4-dimethylstyrene andother halogen-free substituted styrenes such as α-methylstyrene.

Component C.2)

The polyalkylene terephthalates of component C.2) are reaction productsof aromatic dicarboxylic acids or of their reactive derivatives, such asdimethyl esters or anhydrides, and of aliphatic, cycloaliphatic oraraliphatic diols, and also mixtures of these reaction products.

Preferred polyalkylene terephthalates contain at least 80 wt. %,preferably at least 90 wt. %, based on the dicarboxylic acid componentof terephthalic acid groups and at least 80 wt. %, preferably at least90 wt. %, based on the diol component, of ethylene glycol and/or1,4-butanediol groups.

In addition to terephthalic esters, the preferred polyalkyleneterephthalates may contain up to 20 mol-%, preferably up to 10 mol-%, ofgroups from other aromatic or cycloaliphatic dicarboxylic acids having 8to 14 C atoms or from aliphatic dicarboxylic acids having 4 to 12 Catoms such as, for example, groups from phthalic acid, isophthalic acid,naphthalene-2,6-dicarboxylic acid, 4,4′-diphenyldicarboxylic acid,succinic acid, adipic acid, sebacic acid, azelaic acid,cyclohexanediacetic acid.

In addition to ethylene. glycol groups and 1,4-butanediol groups, thepreferred polyalkylene terephthalates may contain up to 20 mol-%,preferably up to 10 mol-%, of other aliphatic diols having 3 to 12 Catoms or of cycloaliphatic diols having 6 to 21 C atoms, for example,groups from 1,3-propanediol, 2-ethyl-1,3-propanediol, neopentylglycol,1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol,3-ethyl-2,4-pentanediol, 2-methyl-2,4-pentanediol,2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol,2,2-diethyl-1,3-propanediol, 2,5-hexanediol,1,4-di(β-hydroxyethoxy)benzene, 2,2-bis(4-hydroxycyclohexyl)propane,2,4-dihydroxy-1,1,3,3-tetramethylcyclobutane,2,2-bis(4-β-hydroxyethoxyphenyl)propane and2,2-bis(4-hydroxypropoxyphenyl)propane (DE-OS 2 407 674, 2 407 776, 2715 932).

The polyalkylene terephthalates may be branched by the incorporation ofrelatively small quantities of trihydric or tetrahydric alcohols or oftribasic or tetrabasic carboxylic acids, for example, in accordance withDE-OS 1 900 270 and U.S. Pat. No. 3,692,744. Examples of preferredbranching agents are trimesic acid, trimellitic acid, trimethylolethaneand trimethylolpropane and pentaerythritol.

Polyalkylene terephthalates which have been prepared exclusively fromterephthalic acid and its reactive derivatives (for example, its dialkylesters) and ethylene glycol and/or 1,4-butanediol, and mixtures of thesepolyalkylene terephthalates, are particularly preferred.

Mixtures of polyalkylene terephthalates contain 1 to 50 wt. %,preferably 1 to 30 wt. %, polyethylene terephthalate and 50 to 99 wt. %,preferably 70 to 99 wt. %, polybutylene terephthalate.

The polyalkylene terephthalates preferably used generally have anintrinsic viscosity of 0.4 to 1.5 dl/g, preferably from 0.5 to 1.2 dl/g,measured in phenol/dichlorobenzene (1:1 parts by weight) at 25° C. in anUbbelohde viscosimeter.

The polyalkylene terephthalates can be prepared by known methods (see,for example, Kunststoff-Handbuch, Volume VIII, pages 695 ff.,Carl-Hanser-Verlag, Munich 1973).

The moulding compositions according to the invention may additionallycontain the conventional additives such as lubricants and mould-releaseagents, nucleating agents, antistatic agents, stabilisers, dyes,pigments, flameproofing agents and/or reinforcing materials.

The moulding compositions according to the invention preferably containat least one phosphorus compound corresponding to formula (III)

In the above formula R⁵, R⁶, R⁷, R⁸, independently of one another, eachdenote optionally halogenated C₁-C₈-alkyl, C₅-C₆-cycloalkyl, C₆-C₁₀-arylor C₇-C₁₂-ar-alkyl; C₆-C₁₀-aryl or C₇-C₁₂-aralkyl are preferred. Thearomatic groups R⁵, R⁶, R⁷ and R⁸ may for their part be substituted byhalogen, preferably chlorine or bromine, and/or alkyl groups, preferablyC₁-C₄-alkyl, in particular methyl, ethyl. Particularly preferred arylgroups are cresyl, phenyl, xylenyl, propylphenyl or butylphenyl as wellas the corresponding brominated and chlorinated derivatives thereof.

X in formula (III) denotes a mononuclear or polynuclear aromatic grouphaving 6 to 30 C atoms. This is derived preferably from diphenols suchas; for example, bisphenol A, resorcinol, hydroquinone, biphenyl ortheir chlorinated or brominated derivatives.

n in formula (III) can, independently of one another, be 0 or 1;preferably n equals 1.

N represents values of from 0 to 30, preferably values from 0.3 to 20,particularly preferably from 0.5 to 10 and in particular from 0.5 to 6.

Both monomeric phosphorus compounds and oligomeric phosphorus compoundsmay be phosphorus compounds corresponding to formula (III). Mixtures ofmonomeric phosphorus compounds and oligomeric phosphorus compounds arelikewise encompassed by formula (III).

Compounds used in particular as monomeric phosphorus compoundscorresponding to formula (III) are organic monomeric phosphates such astributyl phosphate, tris(2-chloroethyl) phosphate,tris(2,3-dibromopropyl) phosphate, triphenyl phosphate, tricresylphosphate, diphenylcresyl phosphate, diphenyloctyl phosphate,diphenyl-2-ethylcresyl phosphate, tri(isopropylphenyl) phosphate,halogen-substituted aryl phosphates, dimethyl methylphosphonite,diphenyl methylphosphonite, diethyl phenylphosphonite,triphenylphosphine oxide or tricresylphosphine oxide.

Mixtures of oligomeric phosphorus compounds corresponding to formula(III), preferably oligomeric phosphates corresponding to formula (III),having n values of from 0.5 to 10, in particular from 0.5 to 6, ormixtures of monomeric phosphorus compounds and oligomeric phosphoruscompounds corresponding to formula (III) are particularly preferablyused as flameproofing agents.

Monomeric and oligomeric phosphorus compounds corresponding to formula(III) are preferably so selected in the mixture that a synergisticeffect is achieved. The mixture generally consists to the extent of 10to 90 wt. % of oligomeric phosphorus compounds and to the extent of 90to 10 wt. % of monomeric phosphorus compounds, preferably monophosphatecompounds corresponding to formula (III).

The monomeric phosphorus compounds are preferably mixed in quantitieswithin the range of 12 to 50 wt. %, in particular of 14 to 40 wt. % andmost preferably of 15 to 40 wt. %, with the complementary quantity ofoligomeric phosphorus compounds.

The above-mentioned phosphorus compounds are preferably used togetherwith fluorinated polyolefins as a flameproofing combination inquantities of from 0.05 to 5 parts by weight.

The fluorinated polyolefins used have high molecular weights and glasstransition temperatures of above −30° C., generally of above 100° C.,fluorine contents of 65 to 76 wt. %, in particular 70 to 76 wt. % andaverage particle diameters d₅₀ of from 0.05 to 1,000 μm, preferably from0.08 to 20 μm. The fluorinated polyolefins generally have a density of1.2 to 2.3 g/cm³. Preferred fluorinated polyolefins arepolytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene,hexafluoropropylene copolymer and ethylene-tetrafluoroethylenecopolymer. The fluorinated polyolefins are known (cf. “Vinyl and RelatedPolymers” by Schildknecht, John Wiley & Sons, Inc., New York, 1962,pages 484-494; “Fluorpolymers” by Wall, Wiley-Interscience, John Wiley &Sons, Inc., New York, Volume 13, 1970, pages 623-654; “Modern PlasticsEncyclopedia”, 1970-1971, Volume 46, No. 10 A, October 1970,McGraw-Hill, Inc., New York, pages 134 and 774; “Modern PlasticsEncyclopedia”, 1975-1976, October 1975, Volume 52, No. 10 A.McGraw-Hill, Inc., New York, pages 27, 28 and 472 and U.S. Pat. Nos.3,671,487, 3,723,373 and 3,838,092).

They can be prepared by known methods, for example, by polymerisation oftetrafluoroethylene in aqueous medium with a catalyst which forms freeradicals, for example, sodium peroxydisulphate, potassiumperoxydisulphate or ammonium peroxydisulphate, at pressures of 7 to 71kg/cm² and at temperatures of 0° C. to 200° C., preferably attemperatures of 20° C. to 100° C. (For further details see, for example,U.S. Pat. No. 2,393,967). Depending on the form of use, the density ofthese materials may be between 1.2 and 2.3 g/cm³ and the averageparticle size between 0.05 and 1,000 μm.

Particularly preferred polyolefins according to the invention aretetrafluoroethylene polymers having an average particle diameter of from0.05 to 20 μm, preferably from 0.08 to 10 μm, and a density of 1.2 to1.9 g/cm³.

Suitable fluorinated polyolefins which can be used in powder form aretetrafluoroethylene polymers having an average particle diameter of from100 to 1,000 μm and densities of 2.0 g/cm³ to 2.3 g/cm³.

Suitable tetrafluoroethylene polymer emulsions are commercial productsobtainable, for example, from the firm DuPont as Teflon® 30 N.

They can be used in the form of a coagulated mixture of emulsions of thetetrafluoroethylene polymer with emulsions of the graft polymers.

To prepare a coagulated mixture, firstly an aqueous emulsion (latex) ofa graft polymer is blended with a finely dispersed emulsion of atetrafluoroethylene polymer; suitable tetrafluoroethylene polymeremulsions typically have solids contents of 30 to 70 wt. %, preferably50 to 60 wt. % and in particular 30 to 35 wt. %.

In the mixture of emulsions, the equilibrium ratio of graft polymer totetrafluoroethylene polymer is from 95:5 to 60:40. The mixture ofemulsions is then coagulated in known manner, for example, by spraydrying, freeze drying or coagulation by addition of inorganic or organicsalts, acids or bases or of organic solvents which are miscible inwater, such as alcohols, ketones, preferably at temperatures of from 20°C. to 150° C., in particular from 50° C. to 100° C. If necessary, themixture can be dried at 50° C. to 200° C., preferably 70° C. to 100° C.

The moulding compositions according to the invention may in additioncontain inorganic reinforcing materials.

The inorganic reinforcing materials used may be glass fibres, optionallycut or ground, glass beads, glass spheres, lamellar reinforcing materialsuch as kaolin, talc, mica, carbon fibres or mixtures thereof. Cut orground glass fibres are preferably used as reinforcing material,preferably having a length of 1 to 10 mm and a diameter of <20 μm, in aquantity of up to 40 parts by weight; the glass fibres are preferablysurface-treated.

The moulding compositions according to the invention may in additionalso contain very finely divided, inorganic powders in a quantity of upto 50 parts by weight, preferably up to 20 and in particular from 0.5 to10 parts by weight.

Very finely divided inorganic compounds comprise compounds of one ormore metals of the first to fifth main groups and the first to eighthsubgroups of the periodic system, preferably the second to fifth maingroups and fourth to eighth subgroups and particularly preferably thethird to fifth main groups and fourth to eighth subgroups, with theelements oxygen, sulphur, boron, phosphorus, carbon, nitrogen, hydrogenor silicon.

Preferred compounds are, for example, oxides, hydroxides, hydrousoxides, sulphates, sulphites, sulphides, carbonates, carbides, nitrates,nitrites, nitrides, borates, silicates, phosphates, hydrides, phosphitesor phosphonates.

Preferred very finely divided inorganic compounds are, for example, TiN,TiO₂, SnO₂, WC, ZnO, Al₂O₃, AlO(OH), ZrO₂, Sb₂O₃, SiO₂, iron oxides,Na₂SO₄,BaSO₄, vanadium oxides, zinc borate, silicates such as Alsilicates, Mg silicates; unidimensional, two-dimensional orthree-dimensional silicates, mixtures and doped compounds are likewiseusable. In addition these particles of nanometric size can besurface-modified with organic molecules in order to obtain a bettercompatibility with the polymers. Hydrophobic or hydrophilic surfaces canbe produced in this way.

The average particle diameters are less than equal to 200 nm, preferablyless than equal to 150 nm and in particular from 1 to 100 nm.

Particle size and particle diameter invariably refer to the averageparticle diameter d₅₀, determined by ultracentrifuge measurements asdescribed by W. Scholtan et al., Kolloid Z. and Z. Polymere 250 (1972),pages 782 to 796.

The inorganic compounds may be in the form of powders, pastes, sols,dispersions or suspensions. By means of precipitation, sols can beobtained from dispersions or powders from suspensions.

The powders can be incorporated into the thermoplastic synthetics byconventional methods, for example, by direct kneading or extrusion ofthe constituents of the moulding composition and the very finelydispersed inorganic powders. Preferred methods are the preparation of amasterbatch, for example, in flameproofing additives, other additives,monomers, solvents, in component A or the coprecipitation of dispersionsof the graft rubbers with dispersions, suspensions, pastes or sols ofthe very finely.divided inorganic materials.

The moulding compositions according to the invention may contain, inaddition to the specified flameproofing agents, from 0.01 to 10 wt. %,based on the total moulding composition, of a further, possiblysynergistically acting flameproofing agent. Further flameproofing agentsmentioned by way of example are halogenated organic compounds such asdecabromobisphenyl ether, tetrabromobisphenol, inorganic halides such asammonium bromide, nitrogen compounds such as melamine,melamine-formaldehyde resins, inorganic hydroxyl compounds such as Mghydroxide, Al hydroxide, inorganic compounds such as antimony oxides,barium metaborate, hydroxoantimonate, zirconium oxide, zirconiumhydroxide, molybdenum oxide, ammonium molybdate, zinc borate, ammoniumborate, barium metaborate and tin oxide, as well as siloxane compounds.

The moulding compositions according to the invention, consisting of theindividual components and optionally additives, are prepared by mixingthe respective constituents together in known manner and bymelt-compounding and melt-extruding the mixtures at temperatures of from200° C. to 300° C. in conventional units such as kneaders, extruders anddouble-shaft screw-type extruders. Where inorganic reinforcing materialsand/or very finely divided powders are added, the masterbatch techniqueis particularly suitable.

The individual constituents can be mixed together in known manner eitherin succession or simultaneously, in fact at about 20° C. (roomtemperature) as well as at more elevated temperatures.

The moulding compositions of the present invention can be used for theproduction of mouldings by injection moulding. Examples of mouldingswhich can be produced are parts of all types of housings, for example,for domestic appliances such as fruit presses, coffee machines, mixers,for office machines, or cover plates for the construction sector andparts for the automobile sector. They are also used in the field ofelectrical engineering, because they have very good electricalproperties.

Another form of processing is the production of mouldings by deepdrawing from previously produced plates and films.

The thermoplastic moulding compositions according to the invention,owing to their very good processing properties and their very goodmechanical properties, in particular their outstanding combination ofthe properties of notched impact strength and high modulus, are suitablefor the production of mouldings of any type, in particular those havingincreased requirements as regards resistance to fracture.

Fields of use are in the data systems technology sector such as, forexample, parts of housings for monitors, printers and copiers. Theserequire mouldings having complicated shapes and relatively thin wallthicknesses.

The present invention accordingly also provides the use of the mouldingcompositions according to the invention for the production of mouldingsof any type, preferably that mentioned above, as well as the mouldingsproduced from the moulding compositions according to the invention.

EXAMPLES

Component A

Linear polycarbonate based on bisphenol A having a relative solutionviscosity of 1,252, measured in CH₂Cl₂ as solvent at 25° C. and in aconcentration of 0.5 g/100 ml.

Component B

The graft polymer B is prepared as follows.

A solution (prepared under nitrogen at 40° C. to 50° C.) of 72 parts byweight of a rubber (poly-cis-butadiene co-block styrene, 11 wt. %styrene, solution viscosity 27.5 mPa·s, 5% solution in styrene) in 257parts by weight styrene, 120 parts by weight acrylonitrile and 229 partsby weight 2-butanone is placed in a 100 l reactor equipped with ananchor mixer (80 rpm) together with 0.95 parts by weight tert.dodecylmercaptan, 0.15 parts by weight 2,5-di-tert. butylphenol and 7.6parts by weight paraffin oil. After the mixture has been heated to 75°C., a solution of 0.57 parts by weight of tert. butyl perpivalate (60%in a mixture of hydrocarbons) and 0.16 parts by weight tert. butylperoctoate in 18 parts by weight 2-butanone is added, followed bystirring for approx. 45 min until the end of the phase inversion(detectable by the decline in the torque). The reaction mixture is thenpolymerised until conversion is complete, in the course of which afurther 0.19 parts by weight tert. dodecylmercaptan (dissolved in 37parts by weight 2-butanone) is added and the temperature is raised (1.5h at 84° C., 1 h at 87° C., 4.5 h at 90° C.). Thereafter 2 parts byweight p-2,5-di-tert. butylphenol propanoic octyl ester (Irganox 1076,Ciba-Geigy) (dissolved in 11 parts by weight 2-butanone) is added asstabiliser.

The solids content of the polymerisation syrup after the end of thereaction is 39 wt. %. The solution is then evaporated in a ZSKlaboratory screw-type evaporator up to a final temperature of 250° C.and granulated. The granular material contains 27 wt. % rubber, the gelcontent (measured in acetone) is 33 wt. % and the average particle sizeof the rubber phase (weight average) is approx. 250 nm.

Component C

Styrene-acrylonitrile copolymer having a ratio of styrene toacrylonitrile of 72:28 and an intrinsic viscosity of 0.55 dl/g (measuredin dimethylformamide at 20° C.).

Emulsion Graft Polymer (Comparison)

Graft polymer of 45 parts by weight of a copolymer of styrene andacrylonitrile in the ratio of 72:28 on 55 parts by weight ofparticulate, cross-linked polybutadiene rubber (average particlediameter d₅₀=0.4 μm), prepared by emulsion polymerisation.

Triphenyl phosphate (Disflamoll TP from the firm Bayer, Leverkusen,Germany)

Antidripping Agent

Tetrafluoroethylene polymer in the form of a coagulated mixturecomprising a SAN [styrene-acrylonitrile] graft polymer emulsion,corresponding to the above-mentioned component, in water and atetrafluoroethylene polymer emulsion in water. The weight ratio of graftpolymer to tetrafluoroethylene polymer in the mixture is 90 wt. % to 10wt. %. The tetrafluoroethylene polymer emulsion has a solids content of60 wt. % and the average particle diameter is between 0.05 and 0.5 μm.The SAN graft polymer emulsion has a solids content of 34 wt. % and anaverage latex diameter d₅₀=0.28 μm.

Preparation

The emulsion of the tetrafluoroethylene polymer (Teflon 30 N from thefirm DuPont) is mixed with the emulsion of the graft polymer and theresulting mixture is stabilised with 1.8 wt. %, based on the polymersolids content, of phenolic antioxidants. At a temperature of 85° C. to95° C. the mixture is coagulated at pH 4 to 5 with an aqueous solutionof MgSO₄ (Epsom salts) and acetic acid, filtered and washed untilvirtually free of electrolyte, then freed from the bulk of the water bycentrifugation and afterwards dried to a powder at 100° C. This powdercan then be compounded with the other components in the units describedabove.

Mould-release Agent

Pentaerythritol stearate

Production and Testing of the Moulding Compositions According to theInvention

All the components of the moulding composition are mixed together in a 3l kneader. The mouldings are produced at 260° C. in aninjection-moulding machine type Arburg 270 E.

The notched impact strength is determined by the method described in ISO180 1A on rods having the dimensions 80×10×4 mm³ at room temperature.

The determination of a_(n) is carried out by the method described in DIN53 453.

The determination of the heat deflection temperature by Vicat B iscarried out in accordance with DIN 53 460 on rods having the dimensions80×10×4 mm³.

The modulus of elasticity is carried out in accordance with ISO 527/DIN53 457.

The stress cracking behaviour (ESC behaviour) is tested on rods havingthe dimensions 80×10×4 mm³. The test medium used is a mixture of 60vol.-% toluene and 40 vol.-% isopropanol. The test specimens arepreviously stretched by means of an arc-shaped template (priorstretching in per cent) and stored in the test medium at roomtemperature. The stress cracking behaviour is assessed from the degreeof prior stretching in the test medium at which fracture occurs after anexposure time of 5 minutes.

The flexural modulus of elasticity is determined by the method describedin DIN 53 457-B3 on rods having the dimensions 80×10×4 mm³.

TABLE 1 Composition and properties of the polycarbonate graft mouldingcompositions Example 1 3 (Compar- (Compar- ison) 2 ison) 4 Components(parts by weight) A 60.0 60.0 69.7 69.7 B — 24.0 — 14.3 Emulsion graftpolymer 24.0 — 7.6 — (Comparison) C 16.0 16.0 6.7 — Triphenyl phosphate— — 11.3 11.3 Antidripping agent — — 4.2 4.2 Mould-release agent 0.5 0.5Properties: Vicat B₁₂₀ [° C.] 120 120 88 90 Notched impact strengtha_(k) 52 77 58 64 [kJ/m²] Joint line strength a_(n) [kJ/m²] — — 12.042.1 Flexural modulus of elasticity 2050 2390 2650 2750 [N/mm²] MVR 240°C./5 kg [ml/ — — 13.7 14.3 10 min] ESC behaviour 0.6 1.0 2.4 * Fractureat [%] *After 10 minutes no fracture

The moulding compositions according to the invention, despite lowerrubber content, show a higher notched impact strength accompanied byhigher modulus of elasticity and improved stress cracking resistance.

What is claimed is:
 1. A thermoplastic moulding composition containing:A 1 to 99 parts by weight of an aromatic polycarbonate or polyestercarbonate; B 1 to 99 parts by weight of at least one graft polymerprepared by solution polymerisation and having a rubber content of from20 to 50 wt. %, based on the graft polymer, and an average particlediameter of the rubber phase of from 80 to 600 nm, wherein said graftpolymer B is prepared by radically polymerising a monomer mixturecomprising, B.1 90 to 20 parts by weight aromatic monoalkenyl compounds,B.2 0 to 50 parts by weight ethylenically unsaturated nitrites, B.3 0 to30 parts by weight of other copolymerisable compounds, in the presenceof 15 to 50 parts by weight, per 100 parts by weight of monomers B.1 toB.3, of a soluble, gel-free butadiene polymer or butadiene-styrenecopolymer,  and in the presence of 50 to 200 parts by weight of asolvent per 100 parts by weight of monomers B.1 to B.3, until thepolymer content of the total mixture is 30 to 70 wt. %, with thoroughmixing and optionally subsequent addition of controller and initiator,wherein the solvent is a mixture of (i) a solvent S1 selected fromaliphatic (C₁-C₈) alcohol, cycloaliphatic (C₅-C₆) alcohol, ketone,ether, ester, nitrile and mixtures thereof, and (ii) a solvent S2selected from aliphatic hydrocarbons, cycloaliphatic hydrocarbonsaromatic hydrocarbons and mixtures thereof;  and C at least one organicphosphorus compound represented by formula (III)

 wherein R⁵, R⁶, R⁷, R⁸, independently of one another, each denoteoptionally halogenated C₁-C₈-alkyl, C₅-C₆-cycloalkyl, C₆-C₁₀-aryl orC₇-C₁₂-aralkyl, X denotes a mononuclear or polynuclear aromatic grouphaving 6 to 30 C atoms, n represents 0 or 1, and N represents valuesfrom 0.3 to
 20. 2. The thermoplastic moulding composition of claim 1further containing a very finely divided compound selected from TiN,TiO₂, SnO₂, WC, ZnO, Al₂O₃, AlO(OH), ZrO₂, Sb₂O₃, SiO₂, iron oxides,Na₂SO₄, BaSO₄, vanadium oxides, zinc borate, Al silicates, Mg silicatesand mixtures thereof.
 3. The moulding composition of claim 1, whereinthe aliphatic hydrocarbon of solvent S2 is selected from C₄-C₁₀aliphatic hydrocarbons, and the cycloaliphatic hydrocarbon of solvent S2is selected from C₄-C₁₀ cycloaliphatic hydrocarbons.
 4. The mouldingcomposition of claim 1, wherein the graft polymer B has a rubber contentof from 22.5 to 45 wt. % and an average particle diameter of the rubberphase of from 150 to 400 nm.
 5. The moulding composition of claim 1,further containing at least one of the following components: ABSpolymers; vinyl (co)polymers; polyalkylene terephthalates; fluorinatedpolyolefins; and inorganic reinforcing agents.
 6. The mouldingcomposition of claim 1, containing additives selected from at least oneof lubricants, mould-release agents, nucleating agents, antistaticagents, stabilisers, dyes, pigments and flameproofing agents.
 7. Thethermoplastic moulding composition of claim 1 wherein the weight ratioof said solvent S1 to said solvent S2 is 30:70.
 8. The mouldingcomposition of claim 1 further containing a very finely divided compoundof one of the first to fifth main groups and the first to eighthsubgroups of the periodic system, with at least one element selectedfrom among oxygen, sulphur, boron, carbon, phosphorus, nitrogen,hydrogen and silicon.
 9. A method of using the composition of claim 1comprising molding articles therefrom.
 10. A molded article comprisingthe molding composition of claim
 1. 11. The thermoplastic mouldingcomposition of claim 1 wherein said solvent S1 is selected from methylethyl ketone, acetone and mixtures thereof, and said solvent S2 isethylbenzene.